The nursery industry supplies ornamental crops to the consumer by way of large nurseries, which grow the crop for the landscaping and garden centers where consumers and landscapers acquire their plants for planting in consumer's yards.
The nursery industry is a multi-billion dollar industry in the US, with more than 20,000 nurseries nationwide. Evidence suggests that his industry, like many, also conforms to the 80/20-rule, in that 80% of all ornamentals are grown by 20% of all growers nationwide. Plants can be segregated into shrubs and trees, the former of which is almost exclusively grown in plastic containers, and the latter grown both in containers and in the ground (known as ball-and-burlap or B&B nurseries). Container nurseries represent about 60% of the nursery industry, while the B&B portion accounts for the remainder.
Plants grown in containers can be shipped directly to the market without the need for transplanting. Container grown plants produce numerous advantages to the nursery by reducing labor cost, as well as handling, packaging and other operating costs. In addition, growing plants in containers provides comparatively simplified weed control and enables controlled irrigation and fertilization.
Container nurseries range in size from a few acres to a few thousand acres, where the larger nurseries typically comprise operations at multiple sites. Some nurseries specialize in certain varieties while others grow many varieties of plants. Many nurseries clone their own varieties, propagating them, prior to planting them in containers and growing them in the field. Once plant material has sufficiently matured, it is sold to other nurseries, distributors, landscape contractors, and/or retail stores. Some nurseries specialize exclusively in propagation, while others only grow containers—nurseries might even specialize in growing certain ornamental varieties for a short period of time, before reselling them to other nurseries for further maturing before they are resold to the general public.
Container nurseries are located in different growing regions across the US, largely where climate benefits the type plant material grown. Plants are grown in greenhouses and in the field, as needed to provide a productive growing environment for the plant material. In order to maximize the usage of acreage, nurseries in the regions with frost and snow utilize greenhouses in which plants are grown over the winter.
Growing plants in containers does, however, have several disadvantages. While production labor content is, indeed, reduced through containerization of the plant material, substantial production labor is still necessary.
Virtually all container nurseries utilize seasonal immigrant labor, typically from Mexico, in order to meet their production needs throughout the growing seasons. Such labor is getting more difficult to obtain, requiring continued lobbying-effort in Washington, D.C. to guarantee exemptions from the Immigration & Naturalization Service (INS), involves costly recruiting south of the border, transportation to and from their hometowns and their accommodations once in the US and working on site. In addition, the allure for workers to perform tiring and backbreaking work outdoors is fading when the same labor pool is being sought for other better paying and lower exertion jobs in the US economy such as assembly, custodial and other such job categories. Recently, the State of California has actually banned hand weeding of most crops due to worker back injury issues.
A large portion of labor-intensive tasks in container nurseries involves handling of containers. Containers are typically repotted before every growing season, requiring them to be picked up in the field, placed on trailers, brought to a potting shed where they are taken out of their containers and repotted in a larger container with additional soil (so called up-shifting), placed on trailers, driven out to the designated bed (usually an outdoor field area), where they are then placed back on the ground in a variety of different tight/staggered/spaced patterns to allow the plants to grow during the season. The plants are also fertilized and continually watered when in the field. Growers in frigid regions also need to take plants out of greenhouses and perform the up-shifting and spacing operations. All these operations are extremely labor intensive and need to be performed in as compressed a time as possible. Competing for time (typically mostly in early spring) is shipping of finished plant material, which generates the revenue for the nursery. This involves selecting plants, transporting them to the shipping dock and loading trucks. In the case of nurseries in the ‘snow belt’, containers that were placed in the field need to be moved into greenhouses, requiring another intensive labor effort to pick them from the field, transport them via trailer to the greenhouses, and tightly pack them inside the structures to survive the winter months.
The degree to which growers and laborers perform their jobs efficiently has a large impact on the nursery's profit margin and its ability to optimize plant growth and health. Since production labor is the prevalent cost in growing ornamentals (up to 20% to 35% of sales according to large growers), the potential for increasing the competitiveness of the industry through automation in order to reduce manpower requirements, or even smooth out the peak labor requirements, is potentially very large.
Schempf in U.S. Patent Application No. 20020182016 presents results of a survey taken of growers, which provides us a distribution of nursery production labor over various production-related tasks, as follows (where no. 1 rank implies the highest number of laborers required):    1. Moving containerized plants to the canning shed from the growing beds and from the growing beds to the potting shed.    2. Moving containerized plants from the growing beds to the staging (shipping) area.    3. Spacing the containerized plants in the growing beds.    4. Moving containerized plants into and out of the over-wintering houses.    5. Moving containerized plants for pruning plants.    6. Moving excess containerized plants during spacing operations.    7. Other miscellaneous tasks (including potting, weeding, spraying, and fertilizing).
One need for production labor that challenges growers due to its unpredictable nature is that associated with returning overturned containerized plant material to its normal upright condition following windstorms. Particulate fertilizer applied to the surface of the soil in the plant containers is spilled on overturning of plant containers. Such spilled fertilizer, which is often a substantial amount in total across the nursery, is often washed away by rain, rendering it an unrecoverable loss and adding substantially to nursery pollutant runoff. Even if the spilled fertilizer remains on the ground adjoining the overturned plants, labor to recover it and return it to the plant containers is substantial.
Uncontrolled overturning of containers also can damage the associated plant material and create the potential for spread of disease.
Other disadvantages of growing free-standing containerized plant material involve irrigation and other broadcast application of chemicals (fertilizer, pesticide, herbicide, etc), whether liquid or solid particulate in nature. The soil mixture used for container grown plants usually has poor water retention so that irrigation must be regularly carried out to prevent the roots from becoming too dry. Such irrigation is typically accomplished by broadcast sprinkling, which results in the majority of applied water missing spaced plant containers. In most cases, spilled irrigation water flows to a retention pond where it can be reclaimed and reused. However, costs of electrical or other energy to run the one or more pumps that typically supply the spilled irrigation water is not recovered. Costs associated with wear of the irrigation system delivering the spilled water are also not recovered. Further, water losses still occur due to evaporation and percolation of at least part of the spilled irrigation water as it runs downhill along its drain paths to the retention pond, particularly in dry locales of relatively low humidity, where the water is needed most and is, thus, typically relatively expensive. Further still, reclaimed water, potentially originating from many areas within a nursery, has the potential to spread disease.
Disadvantages similar to those of broadcast irrigation apply also to broadcast application of chemicals. Spillage of such materials further potentially contributes adversely to pollution in nursery site runoff, particularly following rain sufficient to cause overflow of the nursery's one or more retention ponds.
Beeson, Haman, Knox, Smajstrla, and Yeager in U.S. Pat. No. 6,415,549 present a plant container and container attachment yielding a funnel-shaped container upper opening for collecting otherwise spilled irrigation water and for attachment to adjoining like containers for increasing container orientation stability. The container attachment, while relatively effective at collecting otherwise spilled irrigation water, contemplates substantial additional labor for implementation, which quickly negates water savings.
In addition, above ground containers of containerized plants are often in direct sunlight and wind, which contribute to rapid water evaporation. Most containers used by wholesale nurseries have thin walls and are constructed of plastic containing carbon black, an ingredient that promotes high container longevity, but makes the containers black in color and, thus, highly absorbent of impinging sunlight's radiant energy. The thin side wall(s) of the container thus become hot in direct sunlight and can scorch root tips approaching the container side wall(s) on the inside, adversely affecting the plant growth potential. Above ground containerized plants in more northern regions are also subject to freezing temperatures that combine with high winds to cause convective heat losses by the containers sufficient to freeze roots of containerized plants, potentially killing the plants.
To minimize these disadvantages associated with container grown plants, many nurseries anchor or bury the containers in the ground. This reduces the risk of the roots freezing and the plant from blowing over in high winds. A significant disadvantage of buried containers is the difficulty of removing the container from the ground before the plants can be shipped. Moreover, the roots from the plant grow outward through the drain holes in the container into the surrounding soil. This increases the amount of effort required to remove the container from the ground and usually results in root damage to the plant. An example of this type of growing system is shown in U.S. Pat. No. 5,007,135. This growing system provides a sufficiently large opening in the container to encourage the roots to grow outwardly into the surrounding soil. A shovel or other tool cuts the roots enabling removal of the container from the ground, inherently resulting in damage to the root system.
In recent years, many nurseries have used a below ground system where an empty container is buried in the ground and a growing container containing the plant is placed in the buried container. This system is often referred to in the industry as a pot-in-pot system. The system has several advantages over other growing systems. In particular, the pot-in-pot type system provides protection for the roots to resist freezing and from drying out in the sun. In addition, the buried container anchors the plant container and reduces the risk of the plants from overturning in high winds.
As in other below ground growing systems, the roots from the growing container often grow outward from the drain holes into the below ground container. The below ground container is required to have drain holes to prevent excess water from remaining in the container which will otherwise cause the roots to rot, potentially killing the plant. Often times the roots from the growing container will grow outward through the drain holes of the below ground container and into the surrounding soil. When this occurs, it is difficult to remove the growing container from the below ground container since the containers are now tangled with the root system. In extreme like situations the growing container cannot be separated from the below ground container without removing both containers from the ground and cutting the roots. This disadvantage increases the labor costs and damages the root system of the plant.
Another disadvantage of in-ground pot-in-pot systems is a lack of means of collecting and funneling broadcast applications to the containerized plants, resulting in costs of broadcast application spillage or of increased labor for direct application to the containerized plants. Low-flow drip irrigation systems are often used on larger such containers, but necessitate substantial labor for setup.
Another disadvantage of in-ground pot-in-pot systems is the potential for the ground in which said systems are mounted to have poor percolation, resulting in significant retention of rainwater in said pot-in-pot system and associated resulting rot of roots of incorporated containerized plants, reducing yield.
Another disadvantage of in-ground pot-in-pot systems, particularly in growing smaller plant material, is the lowering of potted plant foliage to a point nearer the ground, where it either must compete with proximal weeds for sunlight or may be damaged by weed eradication equipment, wherein such weeds tend to grow in soil exposed through breeches in or in the absence of typical plastic weed prevention sheeting material by the socket pots, increasing labor and weed control chemicals.
Another disadvantage of in-ground pot-in-pot systems, particularly in growing smaller plant material, is the relatively close spacing of open socket pots needed to maximize bed space utilization, such spacing resulting in awkward and potentially hazardous manual interaction with bed due to the plurality of essentially open holes in the bed.
Another disadvantage of in-ground pot-in-pot systems is the tendency for socket pots to become at least partially filled with clippings and other debris following crop harvest, resulting in additional labor to clear such debris for proper nesting and drainage of subsequently incorporated containerized plants.
Schempf in U.S. Patent Application No. 20020182016 offers an example of a machine for semi-automatically transferring containerized plants between a bed and trailer in the interest of reducing nursery production labor. However, significant labor is still required for a portion of the proposed container handling operation and to address machine mishandling of containers, which Schempf, in related reports, indicates affect between 0.4% and 2.3% of containers handled, i.e., typically at least one container out of every 250.
Examples of various plant growing containers are disclosed in U.S. Pat. No. 6,038,813 to Moore et al, U.S. Pat. No. 4,106,235 to Smith, U.S. Pat. No. 5,279,070 to Shreckhise et al, U.S. Pat. No. 5,099,609 to Yamauchi and U.S. Pat. No. 1,665,124 to Wright and Italian Patent No. 681968 and French Patent No. 427,391. These patents disclose plant container systems having a plant container and a receptacle container for receiving the plant container and holding water for supplying water to the plant. U.S. Pat. No. 5,515,783 to Peng, U.S. Pat. No. 4,232,482 to Watt et al, U.S. Pat. No. 4,027,429 to Georgi and U.S. Pat. No. 1,533,342 to Schein disclose growing containers having a tray or other container below the plant container for collecting water. These containers do not provide a system for preventing the roots of the plant from becoming entangled with the other container.
Accordingly, there is a continuing need in the industry for improved containerized plant growing system that overcomes the above disadvantages.